In recent years, self-service stations have proliferated in response to a demand for low cost motor vehicle fuel. Cost savings are realized by the customer pumping gas himself and subsequently paying the service station attendant. Self-service stations have, however, created certain problems.
One of the major problems is the fire hazard associated with fuel spilled on the ground around the fuel dispenser. The most hazardous fuel spills result when a customer drives his car away from the fuel dispenser without having first removed the nozzle from the fuel tank and shutting off the pump. This can result in the hose rupturing and fuel being pumped onto the ground around the dispenser. Because of the advent of dispensers which measure and totalize fuel volumes pumped, an accident such as this can result, not only in a serious fire hazard, but in a loss of a record of the volume of fuel dispensed prior to the accident.
Several efforts have been made to ameliorate this problem. For instance, U.S. Pat. No. 1,864,233 discloses a device for cutting off fuel flow from a fuel dispenser in an emergency. The device includes a valve having an operating handle connected via a cable to the dispensing hose adjacent its connection to the dispenser. In the event that someone should drive away with the nozzle in the fuel tank, the hose is pulled away from the dispenser and this, in turn, pulls on the cable and automatically closes the fuel supply valve. U.S. Pat. Nos. 1,857,969 and 2,211,476 both disclose automatic fuel flow shut-off devices utilizing either a pneumatic or an electrical actuator operated by a service station attendant while filling a fuel tank. U.S. Pat. No. 2,070,506 discloses another type of automatic shut-off device which utilizes a flexible member that yields under abnormal strain to actuate a switch for shutting off power to the pump in the event that the dispensing hose is hooked by an automobile bumper and pulled away from the dispenser. A pressure responsive automatic fuel shut-off device is disclosed in U.S. Pat. No. 2,880,909.
Whle each of the aforementioned patented devices may function satisfactorily for its intended purpose, there is an ever present demand for an emergency fuel flow shut-off device which is relatively simple in construction, automatic and positive in actuation, and easy to install and maintain.